81503965 has 4 divisors (see below), whose sum is σ = 97804764. Its totient is φ = 65203168.

The previous prime is 81503951. The next prime is 81504013. The reversal of 81503965 is 56930518.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32867289 + 48636676 = 5733^2 + 6974^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81503965 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8150392 + ... + 8150401.

It is an arithmetic number, because the mean of its divisors is an integer number (24451191).

Almost surely, 2^81503965 is an apocalyptic number.

It is an amenable number.

81503965 is a deficient number, since it is larger than the sum of its proper divisors (16300799).

81503965 is a wasteful number, since it uses less digits than its factorization.

81503965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16300798.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 81503965 is about 9027.9546410026. The cubic root of 81503965 is about 433.5703538965.

The spelling of 81503965 in words is "eighty-one million, five hundred three thousand, nine hundred sixty-five".